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Is gravity just entropy rising? Long-shot idea gets another look

quantamagazine.org

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Re: Is gravity just entropy rising? Long-shot idea gets another look

#151
post #138

Entropic gravity is a compelling framework. I think that most Physicists admit that it would be nice to believe that the yet unknown theory of everything is microscopic and quantum mechanical, and that the global and exquisitly weak force of gravity emerges from that theory as a sort of accounting error. But there are so many potential assumptions baked into these theories that it's hard to believe when they claim, "…

Jacobson showed that thermodynamics + special relativity = GR. Those are very very general assumptions, so general that it’s hard to even consider what else you might ask for.

Ooh, link?

Re: Is gravity just entropy rising? Long-shot idea gets another look

#152
post #41
post #40

As an experimental physicist, I refuse to get excited about a new theory until the proponent gets to an observable phenomenon that can fix the question.

The problem with emergent theories like this is that they _derive_ Newtonian gravity and General Relativity so it’s not clear there’s anything to test. If they are able to predict MOND without the need for an additional MOND field then they become falsifiable only insofar as MOND is.

If such a theory makes no new predictions but is simple / simpler than the alternative, then it is a better theory.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#153
Couldn’t it be a byproduct of frame dragging? Any massive object that spins is pulling stuff into it by forcing things to rotate in some kind of space time whirlpool?

This means if something massive doesn’t spin, it would have no gravity, but isn’t everything large enough to have gravity in space pretty much spinning?

Re: Is gravity just entropy rising? Long-shot idea gets another look

#154
post #138

Earlier quoted context omitted.

Jacobson showed that thermodynamics + special relativity = GR. Those are very very general assumptions, so general that it’s hard to even consider what else you might ask for.

Ooh, link?

https://arxiv.org/abs/gr-qc/9504004

Re: Is gravity just entropy rising? Long-shot idea gets another look

#155
post #41

Earlier quoted context omitted.

The problem with emergent theories like this is that they _derive_ Newtonian gravity and General Relativity so it’s not clear there’s anything to test. If they are able to predict MOND without the need for an additional MOND field then they become falsifiable only insofar as MOND is.

Please, how is the article related to MOND's theories?

u/lewdwig's point was that if an emergent gravity theory made the sorts of predictions that MOND is meant to, then that would be a prediction that could be tested. The MOND thing is just an example of predictions that an emergent theory might make.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#156

Couldn’t it be a byproduct of frame dragging? Any massive object that spins is pulling stuff into it by forcing things to rotate in some kind of space time whirlpool? This means if something massive doesn’t spin, it would have no gravity, but isn’t everything large enough to have gravity in space pretty much spinning?

Descartes had a similar idea, but as far as I remember, it requires ether.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#157

This seems backwards. Entropy is a dispersive force — it favors distribution and disorder. But the universe clumps. Planets, stars, galaxies — all of them are low-entropy configurations. So how did scattered dust particles form the planet we’re standing on… through entropy? If gravity is just emergent from entropy, then it should be fighting against planet formation, not causing it. There’s a missing piece here — may…

Entropy isn't a force. It doesn't "favor" anything. Its a property of statistics, information, and distributions. Also why does this have that particular ChatGPT social media post rhythm to it? Please, Lord, tell me we haven't reached the point where people are writing HN comments w/ AI.

Here's the non-ChatGPT rant that I was attempting to not spew all over the internet.

> “There’s some kind of gas or some thermal system out there that we can’t see directly,” >

Posit that there’s something we don’t know about, and we’re supposing it’s gas-like. This is what I like to refer to as “imagination”, and it’s a great way to start thinking about problems. The fact that it’s showing up in an article suggests they didn’t get much further than imagination, but I’ll keep reading…

> “But it’s randomly interacting with masses in some way, such that on average you see all the normal gravity things that you know about: The Earth orbits the sun, and so forth.” >

Cool. We’re back on everything being “random” again. Modern interpretations of quantum mechanics has really torn a hole in the idea of causality by replacing it with the idea that we can’t explain why things happen, but we CAN model it statistically, so we’ll assume the model is right and stop looking for causal relationships entirely.” It’s lazy pessimistic psuedo-science, and I don’t buy it. I don’t outright REFUTE it, but I’m not basing my understanding of nature on it just because a bunch of smart people decided to stop looking.

On the paper the article refers to:

> Consider a pair of massive pistons with a non-interacting gas between them, as in Fig. 1. >

Cool. Happy to consider it. But I am curious… Are there existing examples of particles that do not interact with particles of like kind? Neutrinos and Photons come to mind. But has anyone proven that they don’t interact, or are we just assuming they don’t interact because we haven’t put the effort in to try and detect interactions? But sure, let’s consider the possibility.

> What this exercise demonstrates is that the two pistons feel an effective force between them, namely the pressure, which is mediated by the gas rather than some fundamental quantized field. >

Honestly? I love this. I don’t care about “fields” at all, personally. I feel like it’s more intuitive to think of fields as reinforcement of particle interactions over time and space. An electon moves? So do all of the others. A lot of them move the same way? The others feel that combined movement at distance according to C. Magnetic flux? Interplay of electron inertia reinforcment delayed by the time it takes for the repulsive forces to make their way around a coil (or whatever other medium according to it’s influence) and allow spin to align. Falsifiable? Yes. Relevant intuitive observation? Yes. Taken the time to write out the math myself in languages I don’t know? No.

> >

Cool. I’m almost certain that if I took the time to check their math, it would be meaningfully accurate and absolutely show that this is a way you can view gravity.

But let me ask you… Why the hell would anyone want to think about gravity like that, and why are we trying to explain things in terms of entropy when it clearly has no applications outside of “well, I guess everything is left up to chance, and there’s nothing left to be discovered.” I reject this hypothesis. I reject the idea that everything we see, feel, hear, and know was at one point non-existant, and somehow emerged at this level of complexity such that we are capable of not only cognition but also direct observation of physical phenomena while simultaneously being physical phenomena ourselves. There is something else. And no, it’s not “God”. But it sure as hell isn’t “everything’s just falling apart in interesting ways”. And I get that that’s not the “full idea” behind entropy, but it is entropy’s brand identity, and it is the implication behind entropy as the driving force of nature (sorry, I used force again. I forget we're not allowed to say that about the thing we're using to explain how all of the real forces emerge. my bad). Heat death of the universe as a result of entropy? I’m onboard. Red shift? I get it. Entropy is a great “welp I guess that’s the reason again”, but the mental gymnastics it takes to represent gravity as a result of this? Give me a freaking break.

There’s a simpler explanation for all of this that models well across domains, and nobody is willing to admit it because it doesn’t fit the narrative. Phase-lock. Waveforms that mesh together in torsional space time reinforce each other, sometimes purely locally through identity changes (fusion), and sometimes via interdependant standing waves (non-fundamental particles, atoms, molecules, etc etc). Entropy is just what happens when coherence fails to resolve locally and must resolve non-locally (chemical interactions, fission, dielectric breakdown, photoelectric effect). Most things can be modelled this way: as stable geometric configurations of quantum wave functions representing self-reinforcing torsional spacetime harmonics. And if you take a second to consider it, maybe this single paragraph _is_ a more intuitive explanation of gravity, too.

Re: Is gravity just entropy rising? Long-shot idea gets another look

#158
post #40

As an experimental physicist, I refuse to get excited about a new theory until the proponent gets to an observable phenomenon that can fix the question.

This is why I'm skeptical of theories like Wolfram's: It feels like an overfit based on this: It produces all sorts of known theories (special relativity, parts of QM, gravity etc), but doesn't make new testable predictions, or new fundamentals. When I see 10 predictions emerge from the theory, and they all happen to be ones we already known of... Overfit.

Jonathan Gorard goes through a handful of testable predictions for the hypergraph stuff here: https://www.youtube.com/watch?v=XLtxXkugd5w

Re: Is gravity just entropy rising? Long-shot idea gets another look

#159

Earlier quoted context omitted.

But where did the Sun got it's low entropy photons to start with? From gravity, empty uniform space has low entropy, which got "scooped up" as the Sun formed. From the Big Bang originally. We don’t know what caused the Big Bang.

The end of the previous Big Bang, a-la Big Bounce ;^) "It's turtles all the way down."

Based on the theory of gravity in the article it's actually, "Archimedes Principle all the way down."

https://en.wikipedia.org/wiki/Archimedes%27_principle

Re: Is gravity just entropy rising? Long-shot idea gets another look

#160
Entropic gravity is like the "brazil nut effect" [0] [1]. The idea is that if you shake a glass full of different sized nuts, the large ones will rise to the top.

From what I understand, this is because larger objects have more mass, moving slower when shaked, so as the larger (brazil nuts) don't move as much relative to the smaller ones (peanuts), and because of gravity, there's a cavity left under the brazil nut which gets filled in with peanuts.

For entropic gravity, the idea is that there's a base density of something (particles? sub-atomic particles?) hitting objects in random ways from all directions. When two large massive objects get near each other, their middle region will have lower density thus being attracted to each other from particles hit with less frequency from the lower density region. They sort of cast a "shadow".

I'm no physicist but last time I looked into it there were assumptions about the density of whatever particle was "hitting" larger massive objects and that density was hard to justify. Would love to hear about someone more knowledgeable than myself that can correct or enlighten me.

As an aside, the brazil nut effect is a very real effect. To get the raisins, you shake the raisin bran. To get gifts left from your cat, you shake the kitty litter. It works surprisingly well.

[0] https://en.wikipedia.org/wiki/Granular_convection

[1] https://www.youtube.com/watch?v=Incnv2CfGGM

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